On Thu, Nov 11, 2010 at 10:00 AM, Benny Halevy <bhalevy@xxxxxxxxxxx> wrote:
> On 2010-11-04 17:22, Fred Isaman wrote:
>> This prepares for future changes, where the layout state needs
>> to change atomically with several other variables. In particular,
>> it will need to know if lo->segs is empty. Moreover, the
>> layoutstateid is not really a read-mostly structure, as it is
>> written on each LAYOUTGET.
>>
>> Signed-off-by: Fred Isaman <iisaman@xxxxxxxxxx>
>> ---
>> fs/nfs/callback_proc.c | 8 +++---
>> fs/nfs/nfs4xdr.c | 2 +
>> fs/nfs/pnfs.c | 55 ++++++++++++++---------------------------------
>> fs/nfs/pnfs.h | 4 +--
>> 4 files changed, 24 insertions(+), 45 deletions(-)
>>
>> diff --git a/fs/nfs/callback_proc.c b/fs/nfs/callback_proc.c
>> index 84c5a1b..3e022a8 100644
>> --- a/fs/nfs/callback_proc.c
>> +++ b/fs/nfs/callback_proc.c
>> @@ -135,12 +135,11 @@ static bool
>> pnfs_is_next_layout_stateid(const struct pnfs_layout_hdr *lo,
>> const nfs4_stateid stateid)
>> {
>> - int seqlock;
>> bool res;
>> u32 oldseqid, newseqid;
>>
>> - do {
>> - seqlock = read_seqbegin(&lo->seqlock);
>> + spin_lock(&lo->inode->i_lock);
>> + {
>> oldseqid = be32_to_cpu(lo->stateid.stateid.seqid);
>> newseqid = be32_to_cpu(stateid.stateid.seqid);
>> res = !memcmp(lo->stateid.stateid.other,
>> @@ -158,7 +157,8 @@ pnfs_is_next_layout_stateid(const struct pnfs_layout_hdr *lo,
>> if (res)
>> res = (newseqid == 1);
>> }
>> - } while (read_seqretry(&lo->seqlock, seqlock));
>> + }
>> + spin_unlock(&lo->inode->i_lock);
>>
>> return res;
>> }
>> diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
>> index 6d9ef2b..b71a482 100644
>> --- a/fs/nfs/nfs4xdr.c
>> +++ b/fs/nfs/nfs4xdr.c
>> @@ -1915,7 +1915,9 @@ encode_layoutreturn(struct xdr_stream *xdr,
>> p = reserve_space(xdr, 16 + NFS4_STATEID_SIZE);
>> p = xdr_encode_hyper(p, args->range.offset);
>> p = xdr_encode_hyper(p, args->range.length);
>> + spin_lock(&args->inode->i_lock);
>> pnfs_copy_layout_stateid(&stateid, NFS_I(args->inode)->layout);
>> + spin_unlock(&args->inode->i_lock);
>> p = xdr_encode_opaque_fixed(p, &stateid.data,
>> NFS4_STATEID_SIZE);
>> p = reserve_space(xdr, 4);
>> diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
>> index 4e5c68b..01ecb95 100644
>> --- a/fs/nfs/pnfs.c
>> +++ b/fs/nfs/pnfs.c
>> @@ -456,7 +456,7 @@ pnfs_set_layout_stateid(struct pnfs_layout_hdr *lo,
>> nfs4_stateid *old = &lo->stateid;
>> bool overwrite = false;
>>
>> - write_seqlock(&lo->seqlock);
>> + assert_spin_locked(&lo->inode->i_lock);
>> if (!test_bit(NFS_LAYOUT_STATEID_SET, &lo->state) ||
>> memcmp(old->stateid.other, new->stateid.other, sizeof(new->stateid.other)))
>> overwrite = true;
>> @@ -470,54 +470,34 @@ pnfs_set_layout_stateid(struct pnfs_layout_hdr *lo,
>> }
>> if (overwrite)
>> memcpy(&old->stateid, &new->stateid, sizeof(new->stateid));
>> - write_sequnlock(&lo->seqlock);
>> -}
>> -
>> -static void
>> -pnfs_layout_from_open_stateid(struct pnfs_layout_hdr *lo,
>> - struct nfs4_state *state)
>> -{
>> - int seq;
>> -
>> - dprintk("--> %s\n", __func__);
>> - write_seqlock(&lo->seqlock);
>> - do {
>> - seq = read_seqbegin(&state->seqlock);
>> - memcpy(lo->stateid.data, state->stateid.data,
>> - sizeof(state->stateid.data));
>> - } while (read_seqretry(&state->seqlock, seq));
>> - set_bit(NFS_LAYOUT_STATEID_SET, &lo->state);
>> - write_sequnlock(&lo->seqlock);
>> - dprintk("<-- %s\n", __func__);
>> }
>>
>> /* Layoutreturn may use an invalid stateid, just copy what is there */
>> void pnfs_copy_layout_stateid(nfs4_stateid *dst, struct pnfs_layout_hdr *lo)
>> {
>> - int seq;
>> -
>> - do {
>> - seq = read_seqbegin(&lo->seqlock);
>> - memcpy(dst->data, lo->stateid.data, sizeof(lo->stateid.data));
>> - } while (read_seqretry(&lo->seqlock, seq));
>> + assert_spin_locked(&lo->inode->i_lock);
>> + memcpy(dst->data, lo->stateid.data, sizeof(lo->stateid.data));
>
> This function is just redundant now.
> Let's just open code its two users.
>
> Benny
>
OK.
Fred
>> }
>>
>> void
>> pnfs_get_layout_stateid(nfs4_stateid *dst, struct pnfs_layout_hdr *lo,
>> struct nfs4_state *open_state)
>> {
>> - int seq;
>> -
>> dprintk("--> %s\n", __func__);
>> - do {
>> - seq = read_seqbegin(&lo->seqlock);
>> - if (!test_bit(NFS_LAYOUT_STATEID_SET, &lo->state)) {
>> - /* This will trigger retry of the read */
>> - pnfs_layout_from_open_stateid(lo, open_state);
>> - } else
>> - memcpy(dst->data, lo->stateid.data,
>> - sizeof(lo->stateid.data));
>> - } while (read_seqretry(&lo->seqlock, seq));
>> + spin_lock(&lo->inode->i_lock);
>> + if (!test_bit(NFS_LAYOUT_STATEID_SET, &lo->state)) {
>> + int seq;
>> +
>> + do {
>> + seq = read_seqbegin(&open_state->seqlock);
>> + memcpy(dst->data, open_state->stateid.data,
>> + sizeof(open_state->stateid.data));
>> + } while (read_seqretry(&open_state->seqlock, seq));
>> + set_bit(NFS_LAYOUT_STATEID_SET, &lo->state);
>> + } else
>> + memcpy(dst->data, lo->stateid.data,
>> + sizeof(lo->stateid.data));
>> + spin_unlock(&lo->inode->i_lock);
>> dprintk("<-- %s\n", __func__);
>> }
>>
>> @@ -791,7 +771,6 @@ alloc_init_layout_hdr(struct inode *ino)
>> lo->refcount = 1;
>> INIT_LIST_HEAD(&lo->layouts);
>> INIT_LIST_HEAD(&lo->segs);
>> - seqlock_init(&lo->seqlock);
>> lo->inode = ino;
>> return lo;
>> }
>> diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
>> index 000acf0..de4eaa8 100644
>> --- a/fs/nfs/pnfs.h
>> +++ b/fs/nfs/pnfs.h
>> @@ -96,7 +96,6 @@ struct pnfs_layout_hdr {
>> struct list_head layouts; /* other client layouts */
>> struct list_head segs; /* layout segments list */
>> int roc_iomode;/* return on close iomode, 0=none */
>> - seqlock_t seqlock; /* Protects the stateid */
>> nfs4_stateid stateid;
>> unsigned long state;
>> struct rpc_cred *cred; /* layoutcommit credential */
>> @@ -224,9 +223,8 @@ static inline int lo_fail_bit(u32 iomode)
>>
>> static inline void pnfs_invalidate_layout_stateid(struct pnfs_layout_hdr *lo)
>> {
>> - write_seqlock(&lo->seqlock);
>> + assert_spin_locked(&lo->inode->i_lock);
>> clear_bit(NFS_LAYOUT_STATEID_SET, &lo->state);
>> - write_sequnlock(&lo->seqlock);
>> }
>>
>> static inline void get_lseg(struct pnfs_layout_segment *lseg)
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